imgManager - gallerymanager - problem

Hello out there.

Im trying to extend my application with the imgManager module (also known as gallerymanager), but are faced with some problems. If I run it from the web browser without any kind of debugging tools, it all works fine, except that when Im in the gallery administration tab. If i press the (+) plus button to add a new gallery, at first it seems to work, but when i press submit OR x to close tab, it prevents me from doing anything at all after that. I then cant go back and forth between the Uploaded Images and Image Uploader tabs. It gets stucked and I cant do anything. Besides, the same thing occurs if i press the Update gallery button.

If I run it with FireBug, I get this message:

$.fn.yiiGridView is undefined (line 708) [if I press the (+))


    $.fn.yiiGridView is undefined (line 536) [if I press the Update)

What am I doing wrong? Everything but the Ajax concerning gallery administration works?

Hope someone can put me in the right direction ;)